1. Field of the Invention
The present invention relates to a structure for connecting a flexible or resin tube to an end portion of a metal pipe.
2. Description of the Related Art
Conventionally, there is known a connection-structure as disclosed in Japanese Unexamined Patent Publication No. 2006-090416. In this connection-structure, an end portion of the metal pipe is provided with at least two radially enlarged portions, and a seal ring is positioned in an annular groove formed between the radially enlarged portions. A flexible tube is fitted to the metal pipe such that the tip portion of the flexible tube passes over the two radially enlarged portions.
In the conventional structure, however, the tip portion of the flexible tube tends to expand because of an operation in which the flexible tube is connected to the metal pipe, so that a gap is formed between the flexible tube and the metal pipe, increasing the possibility for water or dust to accumulate in the gap. Due to this, the metal pipe rusts easily, and therefore, it is necessary to use material for the metal pipe that is resistant to rust, such as stainless steel, or to carry out an operation in which an outer surface of the metal pipe is painted, and so on.